Fluid flow control valve assemblies are commonly used for controlling the flow of a pressurized fluid, such as a hydraulic and pneumatic fluid and the like, into and out of cylinders to extend and retract a load. Conventional control valve assemblies typically include one or more intake ports that can be selectively connected between the fluid source and the load, and a fluid exhaust port that enables fluid to flow from the load into a return tank. Such valves are typically multi-positional to selectively engage one or more ports depending on the desired direction of fluid flow.
One such known fluid flow control valve assembly for operating a high pressure single acting hydraulic cylinder is disclosed in U.S. Pat. No. 4,471,805, the disclosure of which is incorporated by reference as if set forth in its entirety herein for the purposes of general valve assembly operation well known in the art. The ′805 patent discloses a first valve body having a pressure port, an outlet port to a load, and a tank port that can be engaged to select the direction of hydraulic fluid flow. A control handle actuates a second valve body having four control ports to select one of several possible modes of operation (i.e., rapid advance, slow metered advance, hold, and return) to control the hydraulic flow rate.
Conventional high-pressure systems thus require two separate valve assemblies to control the motion of a cylinder, thereby increasing the complexity of the device and necessitating excess cost and resources during fabrication. A further limitation is that the design is unidirectional in that the hydraulic fluid flow rate is only controlled in one direction of fluid flow. Furthermore, construction and operation of such conventional devices is unnecessarily complex and tedious.
It would therefore be desirable to provide a single high-pressure control valve having bi-directional control of the direction of hydraulic fluid flow while also metering the rate of pressurized fluid flow through the valve.